Preparation and characterization of Pd immobilized on the MIL-125-NH2 as an efficient recyclable metal-organic framework in the Suzuki–Miyaura reaction

Abstract

In this study, an efficient heterogeneous palladium was developed by moifying the MIL-125-NH₂ metal-organic framework bromoacetyl bromide and tetraethylenepentamine ligands. The resulting modified framework was then used as a platform for immobilizing Pd nanoparticles (NPs) to generate the Pd@MIL-125-NH-Ac-TEPA nanocomposite. FT-IR, FESEM, EDS, TEM, CHN, TGA, XRD, and ICP-OES were used to identify the structure of the nanocomposite. The characterization findings approve the formation of well-dispersed Pd nanoparticles with a size distribution of 9 to 23 nm. The Pd@MIL-125-NH-Ac-TEPA nanocomposite with 2.97 % loading of Pd exhibited high efficiency in the Suzuki-Miyaura coupling reaction of arylboronic acids with various aryl and heteroaryl halides (chlorides, bromides, and iodides) containing electron-donor and electron-acceptor substituents. The coupling products were obtained in water/ethanol mixture (1:1) as solvent at 60 °C for 30 min in 70–99 % yields. The nanocatalyst can be recovered easily and reused for at least five consecutive runs without losing its activity significantly. The palladium leaching of the reused nanocatalyst was less than 1 %. The results revealed that the introduced nanocatalyst has the potential for other organic transformations.